The maximum density of fresh water occurs at approximately 4°C.
Understanding Water Density
Water, unlike most substances, does not continuously increase in density as it cools. Instead, fresh water reaches its maximum density at a temperature of about 4 degrees Celsius. This means that at 4°C, a given volume of water will weigh the most.
Density and Temperature Relationship
Here is how water density changes with temperature:
- Above 4°C: As water heats up above 4°C, its density decreases. This is a typical behavior for liquids.
- At 4°C: Water reaches its maximum density.
- Below 4°C: Surprisingly, as water cools below 4°C, it becomes less dense. This unusual behavior is due to the formation of hydrogen bonds between water molecules, which push them slightly further apart as they approach freezing.
Why is this important?
This behavior of water has several significant implications:
- Aquatic Life: The fact that ice is less dense than liquid water means it floats. This insulates the water underneath in lakes and oceans, preventing them from freezing solid from the bottom up and allowing aquatic life to survive during cold periods.
- Mixing of Water: This density change drives mixing in water bodies, which is important for nutrient distribution.
Reference
According to Figure 4 from the reference, "The density of fresh water plotted against temperature... The maximum density is at ~4 °C (Figure 4). At both lower and higher temperatures than this the water is less dense."
| Property | Value |
|---|---|
| Maximum Density Temperature | ~ 4 °C |
